Host exposure to microbial pathogens such as viruses, bacteria and fungi trigger the activation of innate immune responses, including the production of type I interferon (IFN) that galvanize early host defense mechanisms as well as invigorate adaptive immune responses involving cytotoxic T cell activity and antibody production. The recognition of pathogenic microbes and the triggering of the innate immune cascade has become the subject of intense research over the past few years. Particular attention has recently focused on the role of the Toll-like receptors (TLRs), which have emerged as key molecules largely expressed by dendritic cells and macrophages, that are responsible for recognizing conserved components of pathogenic microorganisms (referred to as pathogen associated molecular patterns -PAMPs)- and which trigger the production of IFN. However, it has recently been discovered that critically important TLR-independent mechanisms also exist to thwart pathogen infection. Instrumental in these responses are a family of DExD/H helicases that appear critical for effective defense against virus infection. However, the mechanisms of TLR-independent signaling remain complex, with downstream molecular components responsible for facilitating the production of IFN remaining to be identified. Here, we have isolated a new molecule that appears to play a significant role in the regulation of innate immune signaling and which is critical for the production of IFN in response to pathogen infection. For this proposal we thus aim to study the importance of this molecule in innate immune helicase action. Essentially, we aim to: I: determine the importance of DExD/H helicases in innate immunity to pathogen infection, including mechanisms of action. II: To potentially determine the mechanisms of innate signaling mediated by the DExD/H helicases involved in pathogen recognition, we have effectively screened for novel molecules which activate the production of type I interferon (IFN), required for effective innate immunity. We aim to further characterize the importance of such molecules in innate signaling and aim to determine their mechanisms of action. These objectives will shed significant insight into the mechanisms of innate immune signaling and generate concepts useful for the generation of new vaccine and immunotherapeutic strategies. PUBLIC HEALTH RELEVANCE Our grant involves attempting to understand how the body recognizes diseases caused by viruses and bacteria. The proposal also aims to understand how the body induces an appropriate immune response following infection. By understanding these processes, we will gain insight into causes of disease and anticipate being able to develop new vaccine and therapeutic strategies. The study of LGP2 and STING and their interaction with other components in the pathway will provide significant insight about the molecular mechanism of RIG-I/MDA5-mediated IFN production and anti-viral innate immunity and thus is of high significance.